The present invention relates generally to systems and methods for externally determining the air pressure present in a pneumatic tire. More specifically, the present invention provides systems and methods for nonintrusively determining tire pressure for a vehicle utilizing sensors which extract the tire surface contact area and the weight supported by the tire to determine tire pressure.
Typically, the pressure in a tire mounted on a vehicle is measured by attaching a pressure gauge or meter to the tire""s air filling stem, allowing the internal pressure to be sampled. This technique has been used for many years and the cost of performing the measurement is small, but it suffers from several major disadvantages. For example, in attempting to make this direct pneumatic connection, air can be lost from the tire in attaching or removing the pressure gauge. Thus, unless special care is used with repeated testing, pressure will be lost from the tire. Hence, there may be a psychological reluctance on the part of the driver of the vehicle to test the tire. Many drivers may not feel comfortable using a tire gauge, may be reluctant to make a test in bad weather, or the like.
Other tire pressure measurement systems allow for on-board measurement and display of tire pressure. Sensors in or on the tires allow a display unit on the dashboard of a vehicle to present real time tire pressure for all four tires. Such an approach may suffer from several weaknesses, such as, increasing the amount of data with which drivers must contend while driving, distracting the driver from the more important job of driving the vehicle, presenting information when and where little can be done to correct an abnormal situation, complicating tire rotation, and increasing the cost of the vehicle.
The present invention provides systems and methods for externally determining the internal pressure of a vehicle tire without requiring a pneumatic connection to the tire or special hardware attached to the tire or vehicle. In one aspect, sensors may be disposed near gas pumps at a service station or other service area. As a vehicle passes over or stops on the sensors, the weight of the tire and the area of the tire in contact with the bearing surface are determined. From these measurements, the tire pressure can be determined. In this situation, low tire pressure can be addressed by a source of air normally present at most modern service stations. Further, service personnel are also typically present to deal with any tire problems or filling issues.
In one aspect, the measurement is transparent to a driver and presents the tire pressure information in a useful fashion during vehicle refueling. In another aspect, the sensors may be configured in a thin mat or envelope.
A more complete understanding of the present invention, as well as further features and advantages of the invention, will be apparent from the following Detailed Description and the accompanying drawings.